memcpy(yuvImg.data, pYuvBuf, framesize * sizeof(unsigned char));什么意思
时间: 2023-05-27 08:03:20 浏览: 57
这行代码的意思是把 pYuvBuf 指向的 unsigned char 类型的数据复制到 yuvImg.data 中,复制的长度为 framesize * sizeof(unsigned char)。也就是说,将 pYuvBuf 指向的数据作为 yuvImg 的数据,实现了将图像数据从一处拷贝到另一处的功能。其中,memcpy 是 C++ 中的一个函数,可以实现内存复制的操作。
相关问题
C语言按照EtherCAT协议,扫描多个伺服电机程序。MACRAM收发略,不用EtherCAT库。用C语言构建和解析ethercat帧写出程序
由于EtherCAT协议的复杂性,编写EtherCAT通信程序需要对该协议有较深入的理解。以下是一个简单的示例程序,用于扫描多个伺服电机。
```c
#include <stdio.h>
#include <string.h>
#define ETHERCAT_FRAME_SIZE 1518
typedef struct {
unsigned int header[2];
unsigned char data[ETHERCAT_FRAME_SIZE];
} ethercat_frame_t;
typedef struct {
unsigned char ID;
unsigned char len;
unsigned short index;
unsigned char subindex;
unsigned char data[4];
} sdo_t;
void send_ethercat_frame(ethercat_frame_t *frame) {
// 发送EtherCAT帧的代码
}
void receive_ethercat_frame(ethercat_frame_t *frame) {
// 接收EtherCAT帧的代码
}
void send_sdo(unsigned char ID, unsigned short index, unsigned char subindex, unsigned char *data, unsigned char len) {
ethercat_frame_t frame;
sdo_t sdo;
memset(&frame, 0, sizeof(ethercat_frame_t));
memset(&sdo, 0, sizeof(sdo_t));
// 构建SDO帧
sdo.ID = ID;
sdo.len = len;
sdo.index = index;
sdo.subindex = subindex;
memcpy(sdo.data, data, len);
// 构建EtherCAT帧
frame.header[0] = 0x00000000;
frame.header[1] = 0x00000000;
frame.data[0] = 0x02;
frame.data[1] = 0x80 | (sdo.len > 4 ? 0x10 : 0x00) | ((6 + sdo.len) << 4);
frame.data[2] = sdo.ID;
frame.data[3] = sdo.index & 0xFF;
frame.data[4] = (sdo.index >> 8) & 0xFF;
frame.data[5] = sdo.subindex;
memcpy(&frame.data[6], sdo.data, sdo.len);
send_ethercat_frame(&frame);
}
void receive_sdo(unsigned char ID, unsigned short index, unsigned char subindex, unsigned char *data, unsigned char len) {
ethercat_frame_t frame;
sdo_t sdo;
memset(&frame, 0, sizeof(ethercat_frame_t));
memset(&sdo, 0, sizeof(sdo_t));
// 构建SDO帧
sdo.ID = ID;
sdo.len = len;
sdo.index = index;
sdo.subindex = subindex;
// 构建EtherCAT帧
frame.header[0] = 0x00000000;
frame.header[1] = 0x00000000;
frame.data[0] = 0x01;
frame.data[1] = 0x80 | (sdo.len > 4 ? 0x10 : 0x00) | ((6 + sdo.len) << 4);
frame.data[2] = sdo.ID;
frame.data[3] = sdo.index & 0xFF;
frame.data[4] = (sdo.index >> 8) & 0xFF;
frame.data[5] = sdo.subindex;
send_ethercat_frame(&frame);
// 接收EtherCAT帧并解析SDO数据
receive_ethercat_frame(&frame);
memcpy(data, &frame.data[6], len);
}
int main() {
unsigned char data[4];
// 扫描多个伺服电机
for (unsigned char ID = 1; ID <= 32; ID++) {
// 读取伺服电机的状态字
receive_sdo(ID, 0x6041, 0x00, data, sizeof(data));
printf("Motor %d status word: 0x%02X%02X%02X%02X\n", ID, data[3], data[2], data[1], data[0]);
// 设置伺服电机的目标位置
data[0] = 0x00;
data[1] = 0x00;
data[2] = 0x10;
data[3] = 0x00;
send_sdo(ID, 0x607A, 0x00, data, sizeof(data));
}
return 0;
}
```
该程序使用了ethercat_frame_t和sdo_t结构体来表示EtherCAT帧和SDO帧。send_ethercat_frame和receive_ethercat_frame函数用于发送和接收EtherCAT帧。send_sdo和receive_sdo函数则用于构建和解析SDO帧,并利用send_ethercat_frame和receive_ethercat_frame函数进行通信。程序主要通过循环扫描多个伺服电机,并读取其状态字,然后设置其目标位置。
websocket是什么,如何用C语言写一个简单的websocket通信
WebSocket是一种在单个TCP连接上进行全双工通信的协议,它可以使浏览器和服务器之间实现实时通信。WebSocket 在 Web 应用程序中使用越来越广泛,它被广泛应用于在线游戏、视频会议、网络直播等场景。
下面是一个使用C语言编写的简单的WebSocket通信示例:
```c
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define BUF_SIZE 1024
int main(int argc, char *argv[]) {
int server_socket, client_socket;
struct sockaddr_in server_addr, client_addr;
socklen_t client_addr_size;
char buf[BUF_SIZE];
bool is_handshake = false;
// 创建服务器socket
server_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (server_socket < 0) {
perror("socket");
exit(1);
}
// 设置服务器socket地址
memset(&server_addr, 0, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
server_addr.sin_port = htons(8080);
// 绑定服务器socket和地址
if (bind(server_socket, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
perror("bind");
exit(1);
}
// 监听客户端连接
if (listen(server_socket, 5) < 0) {
perror("listen");
exit(1);
}
printf("Server is running on port 8080...\n");
while (1) {
// 接受客户端连接
client_addr_size = sizeof(client_addr);
client_socket = accept(server_socket, (struct sockaddr *)&client_addr, &client_addr_size);
if (client_socket < 0) {
perror("accept");
continue;
}
printf("Client %s:%d connected\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
while (1) {
// 接收客户端发送的数据
int len = recv(client_socket, buf, BUF_SIZE, 0);
if (len < 0) {
perror("recv");
break;
} else if (len == 0) { // 客户端关闭连接
printf("Client %s:%d closed\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
break;
}
if (!is_handshake) { // 如果还没有进行WebSocket握手
// 进行WebSocket握手
char *key = strstr(buf, "Sec-WebSocket-Key: ");
if (key) {
char *end = strstr(key, "\r\n");
if (end) {
char accept_key[BUF_SIZE];
memset(accept_key, 0, sizeof(accept_key));
strncpy(accept_key, key + strlen("Sec-WebSocket-Key: "), end - key - strlen("Sec-WebSocket-Key: "));
strcat(accept_key, "258EAFA5-E914-47DA-95CA-C5AB0DC85B11");
unsigned char sha1_buf[BUF_SIZE];
memset(sha1_buf, 0, sizeof(sha1_buf));
sha1((unsigned char *)accept_key, strlen(accept_key), sha1_buf);
char accept_key_base64[BUF_SIZE];
memset(accept_key_base64, 0, sizeof(accept_key_base64));
base64_encode(sha1_buf, 20, accept_key_base64);
char response[BUF_SIZE];
memset(response, 0, sizeof(response));
sprintf(response, "HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: %s\r\n\r\n", accept_key_base64);
// 发送握手响应
send(client_socket, response, strlen(response), 0);
is_handshake = true;
printf("WebSocket handshake completed\n");
}
}
} else { // 已经完成WebSocket握手
// 解析WebSocket帧数据
int payload_len = buf[1] & 0x7f;
int masking_key_offset = 2;
if (payload_len == 126) {
payload_len = (buf[2] << 8) | buf[3];
masking_key_offset = 4;
} else if (payload_len == 127) {
printf("Payload length > 65535 is not supported\n");
break;
}
unsigned char masking_key[4];
memcpy(masking_key, buf + masking_key_offset, sizeof(masking_key));
unsigned char *payload = (unsigned char *)malloc(payload_len);
memcpy(payload, buf + masking_key_offset + sizeof(masking_key), payload_len);
for (int i = 0; i < payload_len; i++) {
payload[i] ^= masking_key[i % sizeof(masking_key)];
}
// 打印接收到的消息
printf("Received message: %s\n", payload);
// 发送消息给客户端
char message[BUF_SIZE] = "Hello, WebSocket!";
send_websocket_frame(client_socket, message, strlen(message));
free(payload);
}
}
close(client_socket);
}
close(server_socket);
return 0;
}
```
这个示例程序实现了一个简单的WebSocket服务器,它可以接收客户端发送的WebSocket帧数据,并且向客户端发送一条固定的消息。在实际使用中,你需要根据具体的需求进行修改和扩展。